Piston expander



2 Sheets-Sheet l D. M. SMITH is a PISTON EXPANDER Filed Jan. 6, 1940 Illlll :Illll III lllllllll Illlllllll IHIIIHII llylllllIlI lllllllll Oct. 8, 1940.

Patented Oct. 8, 1940 UNITEF) STATES PATENT OFFICE PISTON EXPANDER Dallas M. mitli, Kirkwood, Mo., assignor to McQuay-Norris Manufacturing Company, St. Louis, Mo., a corporation of Delaware Application January 6, 1940, Serial No. 312,751 5 Claims; (01. 309-12) My invention relates to piston expanders and more particularly to piston expanders adapted for use to increase the efifective dimensions of piston skirts to compensate for wear in use.

Furthermore, my present invention is directed particularly to an improvement in piston expanders of the type arranged to exert an expansive force against a substantial portion of the inner surface of the skirt so that the circumference of the piston will be increased evenly and the expan sion will not distort the skirt to make it oval in shape.

My invention in its broadest aspect contemplates a device having a base or carrying part preferably substantially arcuate in shape and extending around one half'of the hollow interior of the skirt but removed from the inner surface thereof, a skirt engaging part carried by but freely movable relative to the base part and means for moving the skirt engaging part away from the base part to exert an expansive force against the inner surface of the skirt.

In the accompanying drawings, wherein similar characters are used to designate similar parts, I have shown several'embodiments of my invention, but it should be understood that the use of the structural features invented by me may take many additional forms without any of the substantial benefits of my invention being lost. In these drawings, Fig. 1 is a view of a piston including one form of my expander; Fig. 2 is a section along the lines 2-2 in Fig. 1; Fig. 3 is a view similiar to Fig. 2, but with the parts in a'diilerent position; Fig. 4 is a section along the lines 4-! in Fig. 3: Fig. 5 is a section along the lines 55 in Fig. 2; and Fig. 6 is a detailed view of the expanding means for the device. Figs. 7 to 12, in.- clusive, show a modified form of my invention and, particularly, Fig. 7 is a view of a piston including the modified form; Fig. 8 is a section 'along the lines 8-4 in Fig. '7; Fig. 9 is a view similar to Fig. 8, but with the parts in a different position; Fig. 10 is a view along the lines l-lii in Fig. 9; Fig. 11 is a view along the lines ll-Il in Fig. 10; and Fig. 12 shows the modified type of expanding means.

Referring to Figs. 1 to 6, inclusive, the piston A has a head B including the usual ring groove C and a skirt D depending therefrom and separated from the head throughout a major portion of its periphery by the circumferentially extending slots E. The skirt D, preferably, is split by the axially extending slot F. The piston also includes theusual pin bosses G to receive the wrist pin upon which the connecting rod H is mounted.

The expander shown in these figures comprises a base or carrying part J, which is arcuate in shape and follows the inner surface of the piston skirt, but is removed therefrom as shown in Fig. 3. Preferably, the ends of the base part J are notched as at J2 to engage and follow the contour of the pin bosses so that the expander will be maintained firmly in place under the conditions outlined below. Carried by the base part J is a skirt engaging part K which is substantially the same shape as the part J, but is freely movable away or toward said part. In this embodiment one end of the part K is welded to an end of the part J.

Movement of the part K is controlled by any suitable expanding means, but in the form shown in these figures, this expanding means, as shown in Fig. 6, is an overthrow cam formed of a single piece of wire bent to provide opposed shafts L, a pair of ofiset knuckles M and connected lever arms N. The base part J has formed therein a pair of bosses P to receive the shafts L. As shown in the figures, when the overthrow cam'is in place and the lever arms N are in the position shown by dotted lines in Fig. 2, no expanding force will be exerted against the skirt engaging part K. However, when the lever arms N are moved into the position shown in Figs. 1, 3, 4 and 5, the knuckles M will be rotated so that the part K will be moved away from the part J to engage and exert a firm expansive force against the inner surface of the piston skirt. The base part J need not be formed of spring material because it is a carrying means only. Preferably, the part K is resilient but even this is not necessary. When the parts K and J are moved away from one another by the overthrow cam into the position shown in Fig. 3, the recessed ends J2 of the part J willfirmly engage the bosses G and the expander will be held firmly in place. By adjustment of the size and shape of the knuckles M ofthe overthrow cam varying degrees of expansive force as generated in the expander will be obtained and, in turn, the amount to which the skirt is expanded with be varied.

The piston shown in Figs. 7 to 11, inclusive, is similar to that shown in the first six figures. Similarly, the base part J is much the same as the base part previously described. However, in this embodiment, the base part J carries a pair of fingers Q which extend upwardly and are hooked to' provide portions engaging in a circumferentially extending slot E of the piston so that the engagement'between the base part and the bosses G is not relied on entirely to maintain the expander in predetermined position in use.

The skirt engaging D 1 R of this form of my expander has inwardly bent tongues 8 each adapted to pass through a slot T formed in the part J. Of course, the skirt engaging part R is freely movable away from or toward the part J A slightly modified form of overthrow cam U, as shown in Fig. 12, is provided with opposed shafts V fitting in bosses W formed in the part J. However, the action of the overthrow cam to move the skirt engaging part B to exert an expansive force against the piston skirt is similar to that of the first embodiment. The part B may have a groove RI extending from top to bottom thereof coincident with the axial slot F in the skirt.

From the above description it will be seen that these and other embodiments of my invention may be used eifectively to increase the diameter of a piston skirt and to expand it to compensate for wear in use.

Preferably, I do not intend to limit myself to the exact details of construction shown because the salient members and parts of an expander embodying my invention may be varied widely in size, shape and arrangement without deviating from the spirit of the appended claims.

What I claim as new and desire to secure by Letters Patent, is:

1. A piston expander comprising a base part carried by said piston and a skirt engaging part substantially following the contour of said skirt and carried by said base part so as to be movable freely relative thereto, and arranged to engage a substantial portion of the inner surface of the piston skirt, and means for moving said skirt engaging part relative to said base part whereby an expansive force will be exerted against said skirt.

2. A piston expander comprising an arcuate shaped base part carried by said piston and following but removed from the inner surface of the piston skirt, a skirt engaging part positioned between the piston skirt and said base part and substantially following the contour of said skirt and said base part, said skirt engaging part being carried by said base part so as to be movable freely relative thereto, and arranged to engage the inner surface of the piston skirt, and means for moving said skirt engaging part outwardly away from said base part whereby an expansive force will be exerted against said skirt.

3. A piston expander comprising an arcuate shaped base part carried by said piston and following but removed from the inner surface of the piston skirt, a skirt engaging part carried by said base part so as to be movable freely relative thereto, and arranged to engage the inner surface of the piston skirt, and an overthrow cam carried by said expander and movable into a position to move said skirt engaging part away from said base part whereby an expansive force will be exerted against said skirt.

4. A piston expander having an arcuate shaped base part arranged to follow the contour of the inner surface of the piston skirt, and having its ends-recessed to engage the pin bosses of the piston, a skirt engaging part carried by said base part so as to be movable freely relative thereto, and arranged to engage the inner surface of the piston skirt, and means for moving said skirt engaging part relative to said base part whereby an expansive force will be exerted against said skirt.

5. A piston expander having anarcuate shaped base part arranged to follow the contour of the inner surface of the piston skirt, and having its ends recessed in engage the pin bosses of the piston, an arcuate shaped skirt engaging part carried by said basepart so as to be movable freely relative thereto, and arranged to engage the inner surface of the piston skirt, and an overthrow cam carried by said base part and arranged to be movable into a position to move said skirt engaging part away from said base part whereby an expansive force will be exerted against said DALLAS M. SMITH. 

